Ultrasonic Thickness Testing

What, Who, When, Where, Why?

What is Ultrasonic Thickness Testing?

An ultrasonic thickness test measures steel thicknesses with a handheld device.  The basic procedure is to enter a vessel, clean a location on the inner shell, use gel to get good reading, obtain and record thickness. This is done in several locations as wear typically differs throughout a vessel.

Who needs to Do Ultrasonic Thickness Testing?

Any company that has pressure vessels (batch rendering cookers are our most common example) should test thicknesses.

An ASME company with engineers on staff who can interpret the results should be utilized to conduct the test.  Alternately, the rendering company can perform their own thickness test and ask an ASME vendor, such as Alloy, for help in analyzing the data.

When does Ultrasonic Thickness Testing need to be performed?

Thickness test should be conducted annually.  They typically are done on Sundays when the plant is shut down; with a vessel that has been cleaned and flushed, and maintaining strict Confined Space Entry safety protocols.

Where is Ultrasonic Thickness Testing performed?

Alloy utilizes a pre-set diagram to show where each measurement needs to be taken.  The drawing utilized is dependent upon the type of vessel being checked.  In all cases, the entire vessel is checked with particular attention given to areas that are typically thin.

Why?

There are several reasons why thickness tests should be taking including:

• Safety – In some cases, the thickness test shows a reading that is below the minimum to safely operate the vessel.  In this instance, a company might be able to run on reduced pressure until the vessel can have its shell replaced or the entire vessel replacement decision is reached.
• Insurance Regulations – Several insurance companies require annual tests.
• Preventative Maintenance/Budget Planning – Many companies utilize Alloy for annual tests.  Cookers show a predictable wear pattern, if they are tested each year.  Utilizing anticipated wear based on several years’ worth of data, companies can predict and plan for cooker reshelling/replacement a year or more in advance.  Therefore, reshellings can be put into annual budgets and a company can know in advance if one, two, three or no reshellings are going to occur in any fiscal year.

Please contact Alloy if you would like to schedule a thickness test for your pressure vessels.